Local Time Hemispheric Asymmetry in Nitric Oxide Radiative Emission During Geomagnetic Activity

Abstract

Abstract The nitric oxide (NO) radiative emission at 5.3 μm cools the thermosphere by conversion of solar energy into infrared radiation subsequently exiting thermosphere. It correctly serves as a natural thermostat . The NO 5.3‐μm emission is even more important during geomagnetic storm events due to huge deposition of heat energy and momentum in the Earth's atmosphere. The Thermosphere, Ionosphere, Mesosphere Energetics, and Dynamics‐Sounding of the Atmosphere using Broadband Emission Radiometry observation of NO 5.3‐μm radiative emission is studied between ±55° geographic latitudes during eight geomagnetic storm events. Two events that occurred during 7–12 November 2004 (Dst = −374 nT) and 23–28 August 2005 (Dst = −184 nT) are analyzed in details. The variation of NO emission during other six storms is also presented. The NO volume emission rate (NO VER) shows an enhancement during storm events. The enhanced NO VER illustrates an equatorward movement with descending peak altitude as one moves toward the equator. The NO infrared radiative flux is calculated by integrating NO VER from altitude of 100 to 155 km. A local time hemispheric asymmetry in both NO VER and NO infrared radiative flux is observed during all geomagnetic storm events.